Phase-Based Localization for Underwater Targets
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Solution Overview
Problem
Autonomous underwater vehicles (AUVs) face challenges in accurately and efficiently determining their location underwater during marine seismic surveys, as they rely on detecting waves from a single source, leading to imprecise or time-consuming positioning.
Innovation Solution
The method estimates the location of an underwater target device using a combination of phase delay, time delay, and orientation of detected acoustic waves, employing volume contraction techniques with contractors to narrow down possible positions, allowing for precise and rapid location determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If triangulation is used with multiple wave sources, then location precision is improved, but device complexity and operational requirements increase
Solution Approach 1:
The patent extracts and utilizes only the phase information from the acoustic signal while eliminating the requirement for multiple wave sources. By focusing on the phase delay of the signal from a single source combined with AUV orientation data, the system achieves accurate positioning without the complexity of multiple sources or triangulation geometry calculations
Solution Approach 2:
The patent changes the parameter used for positioning from geometric triangulation (requiring multiple sources) to phase-based positioning (using single source with orientation). This parameter change allows the system to determine location using phase delay and orientation angles rather than requiring complex spatial relationships between multiple sources and receivers
2Device complexity
If traditional acoustic positioning is used with single source, then device complexity is reduced, but location precision deteriorates
Solution Approach 1:
The patent merges phase delay information with AUV orientation data (heading, pitch, roll angles) to create a combined positioning approach. This combination allows the system to use a single wave source while achieving precision comparable to or better than traditional methods, as the orientation data provides additional constraints that resolve the ambiguity inherent in single-source phase measurements
3Measurement precision
If more wave sources are deployed, then location precision is improved, but operational constraints and time consumption increase
Solution Approach 1:
The patent performs preliminary calculation of expected phase delays based on AUV orientation and position estimates, then uses these predictions to rapidly refine the position calculation. This preliminary action allows the system to quickly converge on an accurate position without requiring multiple wave sources or iterative measurements over extended periods
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the ambiguity in determining the AUV's location, enabling faster and more precise tracking without impeding its operation, by using phase and time delays in conjunction with orientation to contract the possible location volume effectively.
Implementation Method 1
measuring a phase delay of the signal corresponding to the acoustic waves
Implementation Method 2
measuring a time delay of the signal corresponding to the acoustic waves
Implementation Method 3
detect acoustic waves emitted at a known location
Data Source
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AI summary
Location of underwater moving target device carrying a receiver configured to detect acoustic waves emitted at a known location is estimated such that to be consistent with detected velocity and orientation of the target device, and with a current phase of a signal corresponding to the acoustic waves detected at the target device. A stack including one or more boxes obtained by applying contractors to location boxes is output as the estimate of the location of the moving target device.